V

1.
3,5-Di-tert-butylsalicylaldehyde
–
It is a pale yellow solid. This aldehyde is a block for preparing salen ligands. For example, the ligand for Jacobsens catalyst may be prepared from the appropriate 1. The catalyst is obtained by reaction with manganese acetate and atmospheric oxygen in the presence of a chloride source

2.
Salicylaldehyde
–
Salicylaldehyde is the organic compound with the formula C6H4CHO-2-OH. Along with 3-hydroxybenzaldehyde and 4-hydroxybenzaldehyde, it is one of the three isomers of hydroxybenzaldehyde and this colorless oily liquid has a bitter almond odor at higher concentration. Salicylaldehyde is a key precursor to a variety chelating agents, some of which are commercially important, salicylaldehydes in general may be prepared from the corresponding phenol by the Duff reaction, or by treatment with paraformaldehyde in the presence of magnesium chloride and a base. Salicylaldehyde was identified as a characteristic component of buckwheat. It is also one of the components of castoreum, the exudate from the castor sacs of the mature North American beaver, furthermore, salicylaldehyde occurs in the larval defensive secretions of several leaf beetle species that belong the subtribe Chrysomelina. An example for a beetle species that produces salicylaldehyde is the red poplar leaf beetle Chrysomela populi. Salicylaldehyde is used to make the following, Oxidation with hydrogen peroxide gives catechol, etherification with chloroacetic acid followed by cyclisation gives the heterocycle benzofuran. Salicylaldehyde is converted to chelating ligands by condensation with amines, with ethylenediamine, it condenses to give the ligand salen. Condensation with diethyl malonate gives 3-Carbethoxycoumarin via an aldol condensation

3.
Ethylvanillin
–
Ethylvanillin is the organic compound with the formula C6H3CHO. This colorless solid consists of a ring with hydroxyl, ethoxy, and formyl groups on the 4,3. Ethylvanillin is prepared from catechol, beginning with ethylation to give guethol and this ether condenses with glyoxylic acid to give the corresponding mandelic acid derivative, which by oxidation and decarboxylation, gives ethylvanillin. As a flavorant, ethylvanillin is about three times as potent as vanillin and is used in the production of chocolate

4.
Syringaldehyde
–
Syringaldehyde is an organic compound that occurs in trace amounts widely in nature. Some species of insects use syringaldehyde in their communication systems. Scolytus multistriatus uses it as a signal to find a host tree during oviposition, because it contains many functional groups, it can be classified in many ways - aromatic, aldehyde, phenol. It is a solid that is soluble in alcohol and polar organic solvents. Syringaldehyde can be found naturally in the wood of spruce and maple trees, syringaldehyde is also formed in oak barrels and extracted into whisky, which it gives spicy, smoky, hot and smoldering wood aromas. This compound may be prepared from syringol by the Duff reaction

5.
3-Hydroxybenzaldehyde
–
3-Hydroxybenzaldehyde is one of the three isomers of hydroxybenzaldehyde. It has been prepared from 3-nitrobenzaldehyde in a sequence of nitro group reduction, diazotization of the amine, 3-hydroxybenzyl-alcohol dehydrogenase is an enzyme that uses 3-hydroxybenzyl alcohol and NADP+ to produce 3-hydroxybenzaldehyde, NADPH and H+. A known use of 3-Hydroxybenzaldehyde is in the synthesis of Monastrol

6.
4-Hydroxybenzaldehyde
–
4-Hydroxybenzaldehyde is one of the three isomers of hydroxybenzaldehyde. It can be found in the orchids Gastrodia elata and Galeola faberi and it is also found in vanilla. The Dakin oxidation is a redox reaction in which an ortho- or para-hydroxylated phenyl aldehyde or ketone reacts with hydrogen peroxide in base to form a benzenediol. Overall, the group is oxidized, and the hydrogen peroxide is reduced. P-Hydroxybenzaldehyde dehydrogenase is a found in carrots